Sistema circulatorio y transporte de nutrientes

• Exchange of substances with our environment

Levels of Organization

• Organelle
• Cells
• Tissue
• Organs

Systems Involved in Nutrition

• Digestive
• Circulatory
• Respiratory
• Excretory

Circulatory System

• Transports nutrients and oxygen to all cells of the organism
• Nutrients are absorbed in the digestive system
• Oxygen is acquired in the respiratory system
• Helps to eliminate waste

Structure of the Circulatory System

• Heart: Main organ
• Vessels: Blood vessels (arteries, arterioles, capillaries, venules, and veins)
• Tissues: Blood

Histology of the Heart

• The heart is formed by a tissue called Myocardium
• Composed of multinucleated cells that contract involuntarily and rhythmically

Anatomy of the Heart

• Divided into 4 chambers
• Right atrium: Receives blood from the veins
• Left atrium
• Right ventricle: Releases blood through the arteries
• Left ventricle

Vessels of the Circulatory System

• Veins: Conducts that carries blood to the heart; they have valves that allow circulation
• Arteries: Conducts that exit the heart; regulate their diameter (constricting or dilating)
• Capillaries: Smallest vessels; allow the exchange of substances

Functional Unit: Capillaries

• Facilitates the exchange of substances between blood and cells

Circulation

• In vertebrates, circulation is closed: Blood circulates through a network of blood vessels, without leaving them
• In mammals, it includes 2 circuits

Pulmonary Circulation (Lesser)

• Poor blood in oxygen exits from the right ventricle
• Travels through the pulmonary artery
• Blood rich in oxygen returns to the heart via pulmonary veins
• Arrives at the left atrium

Systemic Circulation (Greater)

• Rich blood in oxygen exits from the left ventricle
• Travels through the aorta artery
• It reaches the whole body
• Poor blood in oxygen returns to the heart via vena cava
• Arrives at the right atrium

Respiratory System

• Its function is to obtain the necessary oxygen for cellular respiration and to eliminate carbon dioxide

Structure of the Respiratory System

• Airways: Nasal passages, pharynx, larynx, trachea
• Lungs
• Bronchi -> Bronchioles -> Alveoli

Pulmonary Ventilation

• Inspiration and expiration allow the passage of air from the atmosphere to the alveoli

Functional Unit: Alveoli

• Air reaches some membranous sacs: Alveoli surrounded by capillaries
• Gaseous exchange between CO2 and O2 also takes place

Gaseous Exchange

• The diffusion of oxygen and carbon dioxide between the alveolus and the capillary occurs due to the difference in concentration

Gaseous Transport

• Oxygen binds to iron atoms (hemoglobin)
• Present in the red blood cells of the blood

Cellular Respiration

Digestive System

• Structures: Mouth, pharynx, esophagus, stomach, small intestine, large intestine
• Function: Ingestion, digestion, absorption, egestion

Function: Ingestion

• Intake of food through the mouth

Function: Digestion

• Transforms food in the digestive tubes

Function: Absorption

• Nutrients pass into the blood

Function: Egestion

• Eliminates waste through the anus

Transformation of Food

• Bolus: After chewing and salivation in the mouth
• Chyme: Action of gastric juices in the stomach
• Chyle: Action of bile and pancreatic juice in the duodenum

Assimilation

• Most of the assimilation takes place in the small intestine thanks to the microvilli in the jejunum and ileum; the duodenum performs absorption but lacks microvilli, while the ileum does not present them

Digestion in the Small Intestine

• There is a process of chemical and mechanical digestion
• The digestion of carbohydrates and proteins is completed in the duodenum
• In the duodenum, fats are digested with the help of bile salts and pancreatic lipase

Enzymes

• Enzymes are proteins that transform complex molecules into simple ones for their absorption
• Carbohydrates into monosaccharides
• Proteins into amino acids
• Lipids into fatty acids

Excretory System

• Consists of eliminating waste produced by cellular metabolism

Excretion

• Lungs: Through the elimination of H2O and CO2
• Liver: Eliminates the pigments through the bile that is produced by the degradation of hemoglobin
• Skin: The sweat glands help regulate the temperature by eliminating metabolic waste

Urinary System

• The urinary system is formed by two kidneys, which send urine to the bladder through the ureters; then, the urine is expelled through the urethra

Kidneys

• The kidneys filter waste substances from the blood
• The renal cortex forms the urine
• The renal pelvis collects it

Functional Unit: Nephron

• The nephron is the functional unit of the kidney
• More than 1 million are in the renal cortex, except for the loop of Henle, which is in the medulla
• Its function is to filter and purify the blood to form urine

Urine Formation

• Filtration
• Reabsorption
• Secretion